TWI793145B - Phosphor-converted white light emitting diodes having narrow-band green phosphors - Google Patents

Abstract

In one aspect, a phosphor converted white light LED comprising a narrow green phosphor rather than a conventional broad green phosphor may simultaneously exhibit high R9, and high Luminance Efficacy of Radiation, optionally without use of a deep red phosphor to maintain desired red color rendering. In another aspect, a phosphor converted white light LED comprising a narrow green phosphor rather than a conventional broad green phosphor may provide an emission spectrum exhibiting a significant dip in the yellow region of the spectrum and thereby provide high red-green contrast without use of a filter. The yellow dip may be shallower than in conventional devices, and the device may therefore be brighter, while maintaining desired CRI and R9.

Description

Phosphor-converted white light-emitting diodes with narrow-band green phosphors

The present invention generally relates to phosphor-converted white light-emitting diodes comprising narrow-band green phosphors.

The ability of a light source to display deep red is measured by measuring R9. Unfiltered incandescent light sources by definition render deep reds extremely well, typically greater than 97. Replacing incandescent light sources tends to strive for true reds. For example, high pressure sodium lamps and old fluorescent lighting tubes often have negative values for R9 and reduce almost any red to a rather dull orange appearance. Early light-emitting diodes (LEDs) got a bad reputation for poor rendering of red. This situation is so obvious that many programs related to LED lighting only require R9>0. This is in contrast to general color rendering index (CRI) requirements, which are typically CRI>80.

In general, general lighting can be made more pleasing by increasing the red-green contrast, for example by removing yellow light which can wash out the appearance of many objects. This phenomenon has been known in the art for many years, dating back at least to US 4,441,046 "Incandescent lamps with neodymium oxide vitreous coatings", where the neodymium oxide coating filters out some of the green and most of the yellow. Based on this work, in 1995, GE released the Enrich® series of incandescent bulbs, and in 2001, renamed the series Reveal®. The incandescent Reveal® product line still exists today, along with the updated Reveal® LED products that still utilize neodymium filters.

Figure 1 shows the normalized emission spectra of a Reveal® incandescent bulb (solid line) and a Reveal® A19 LED bulb (dashed line), which demonstrates the effect of neodymium oxide filters in these products. One of the biggest drawbacks of this method is that it generates photons and then removes a significant portion of the generated photons. This is seen in the rated output of the 60W Reveal® Incandescent (520 lumens) and the Reveal® LED A19 (570 lumens) compared to the 60W equivalent A19's baseline of 800 lumens.

In general, it has become an industry goal to manufacture white-emitting phosphor-converted LEDs whose emission spectra are relatively flat, sloped, and continuous in the range between 500 nanometers (nm) and about 600 nm. Its general shape roughly reflects the emission spectrum of a reference illuminant, eg a black body radiator, such as a standard incandescent. As shown in Figure 1, the neodymium oxide filters used in Reveal® products introduce a dip in the yellow region of the emission spectrum. Such a drop may be characterized by a residual intensity at its lowest value when compared to the maximum intensity of the emission spectrum between 400nm and 700nm, eg about 25% for the incandescent version and about 33% for the LED A19 version.

The red-green contrast ratio does not have a clear measurement in the CRI/Ra system, but it can be captured by the color gamut index measurement (Rg) of the IES TM-30-15 method to a certain extent. Applicants measured an Rg of 109 for Reveal® white heat and 101 for unfiltered white heat. Reveal® LED bulbs were similarly measured at a high Rg value of 104. Surprisingly, despite a good color gamut indication, these bulbs measure relatively poorly on the R9 crimson scale. The drawback of this method is the use of neodymium filters to subtract the large amount of light produced. Photons in the wavelength region affected by these neodymium filters are particularly bright, typically in the range of 512 to 625 lumens per optical watt, compared to a maximum of 683 lumens per optical watt. Reveal® LED bulbs are rated to deliver 570 lumens using 10.5W, while similar correlated color temperature (CCT) and CRI LED bulbs from the Relax® series deliver 800 lumens using their same 10.5W.

Typically, white-emitting phosphor-converted LEDs contain two or sometimes three Broad green or yellow phosphors with a full width at half maximum (FWHM) of about 60 to 100 nm and a peak wavelength of about 500 to 570 nm and a broad green or yellow phosphor having a FWHM of about 70 to 100 nm and a peak wavelength of about 615 to 670 nm or more typically about 625 to 650 nm Phosphor blends of red phosphor combinations.

Red phosphors with peak emission at 625 to 630 nm provide higher efficacy due to better overlap of the red phosphor emission with the photopic response curve of the typical human eye, but this selection of red phosphor emission typically compromises R9. In contrast, red phosphors with peak emission near 650nm provide better red rendering, but at the expense of efficacy, since longer wavelength red emission contributes less to the overall brightness of the LED. There is generally an inverse relationship between the deep red appearance of a light source, as measured by R9, and the spectral efficiency, or spectral luminous efficiency (LER).

In one aspect of the invention, applicants have discovered that a phosphor-converted white LED comprising a narrow green phosphor instead of a conventional broad green phosphor can simultaneously maintain the desired red color rendering without using a deep red phosphor. Show high R9, high CRI and high radiance effect. For example, in such devices, the longest wavelength phosphor peak emission can be shorter than about 635 nm.

In one aspect of the invention, applicants have discovered that a phosphor-converted white LED comprising a narrow green phosphor instead of a conventional broad green phosphor can provide an emission spectrum that exhibits a significant drop in the yellow region of the spectrum, and thus in the yellow region of the spectrum. Provides high red-green contrast without the use of filters. Since this yellow drop is in the light emission and not caused by the filter, no emission power is lost for filtering. Furthermore, applicants have discovered that by using a narrow green phosphor, the yellow drop can be lighter than in prior art products, and the device can therefore be brighter while maintaining the desired CRI and R9 (red color rendering). The lowest intensity in the yellow dip is between about 400 for the device There may be, for example, greater than 25% peak intensity in the total emission spectrum between nm and about 700 nm.

These and other embodiments, features and advantages of the present invention will become more apparent to those skilled in the art when reference is made to the following more detailed description of the invention in conjunction with the accompanying drawings, first briefly described.

Figure 1 shows the normalized emission spectra of a Reveal® incandescent bulb (solid line) and a Reveal® A19 LED bulb (dashed line).

Figure 2 shows the normalized simulated spectrum of a 2700 K LED for a 35nm FWHM with green phosphor emission peaking at 524nm (dotted line), 534nm (dashed line), and 528nm (solid line).

Figure 3 shows the normalized simulated spectrum of a 2700 K LED with a 40nm FWHM of green phosphor emission peaking at 520nm (dotted line), 532nm (dashed line) and 526nm (solid line).

Figure 4A is a plot of duv versus CRI for simulated phosphor converted LEDs comprising blue LEDs, ER6436 red phosphor and green phosphor with peak emission at 532nm and FWHM of 40nm.

Figure 4B is a plot of duv versus CRI for simulated phosphor converted LEDs comprising blue LEDs, ER6436 red phosphor and green phosphor with peak emission at 528nm and FWHM of 40nm.

Figure 4C is a plot of duv versus CRI for simulated phosphor converted LEDs comprising blue LEDs, ER6436 red phosphor and green phosphor with peak emission at 526nm and FWHM of 40nm.

Figure 5 shows 45nm FWHM at 518nm (dotted line), 530nm (dashed line) and normalized simulated spectra of a 2700 K LED emitting from a green phosphor peaking at 524 nm (solid line).

Figure 6 shows the normalized simulated spectra of the 3000 K LED emission from a green phosphor with a 35nm FWHM peaking at 514nm (long and short dash lines), 516nm (dashed line), 518nm (solid line) and 520nm (dotted line).

Figure 7 shows the simulated spectrum (solid line) of a 3000 K LED for green phosphor emission with a 36nm FWHM peaking at 517nm and the measured spectrum (dashed line) of the example phosphor-converted LED characterized in Table 4C.

Figure 8 shows the normalized simulated spectrum of a 3000k LED for a 40nm FWHM with green phosphor emission peaking at 522nm (dotted line), 530nm (dashed line) and 534nm (solid line).

Figure 9A is a graph of duv versus CRI for simulated phosphor-converted LEDs comprising a blue LED, an ER6436 red phosphor, and a green phosphor with peak emission at 530nm.

Figure 9B is a graph of duv versus CRI for simulated phosphor-converted LEDs comprising a blue LED, an ER6436 red phosphor, and a green phosphor with peak emission at 528nm.

Figure 9C is a graph of duv versus CRI for simulated phosphor-converted LEDs comprising a blue LED, an ER6436 red phosphor, and a green phosphor with peak emission at 526nm.

Figure 9D is a graph of duv versus CRI for simulated phosphor-converted LEDs comprising a blue LED, an ER6436 red phosphor, and a green phosphor with peak emission at 522nm.

Figure 10 shows the normalized simulated spectrum of a 3000 K LED for a 45nm FWHM with green phosphor emission peaking at 520nm (dotted line), 524nm (dashed line), and 530nm (solid line).

Figure 11 shows the normalized simulated spectrum of a 3500 K LED for green phosphor emission with a 35nm FWHM peaking at 520nm (dotted line), 518nm (solid line) and 516nm (dashed line).

Figure 12 shows the simulated spectrum (solid line) of a 3500 K LED for green phosphor emission with a 36nm FWHM peaking at 517nm and the measured spectrum (dashed line) of the example phosphor-converted LED characterized in Table 7C.

Figure 13 shows the normalized simulated spectrum of a 3500 K LED for green phosphor emission with a 40nm FWHM peaking at 532nm (dotted line), 528nm (solid line) and 524nm (dashed line).

Figure 14 shows the normalized simulated spectrum of a 3500 K LED for green phosphor emission with a 45nm FWHM peaking at 530nm (dotted line), 526nm (solid line) and 522nm (dashed line).

Figure 15 plots on the horizontal axis CRI and R9 and green phosphor emission peak wavelengths for simulated white phosphor-converted LEDs including blue LEDs, ER6436 red phosphor, and narrow green phosphor.

Figure 16 plots CRI versus duv for simulated white phosphor-converted LEDs comprising a blue LED, ER6436 red phosphor, and a narrow green phosphor with a peak wavelength of 532nm and varying FWHM.

Figure 17 plots CRI and duv for simulated white phosphor-converted LEDs comprising blue LEDs, ER6436 red phosphor, and peak wavelength and variation at 522nm The FWHM of the narrow green phosphor.

Cross References to Related Applications

This application claims U.S. Patent Application No. 15/679,021 filed on August 16, 2017 and entitled "Phosphor-Converted White Light Emitting Diodes Having Narrow Band Green Phosphors" and filed on July 31, 2017 and named Priority to US Provisional Patent Application No. 62/539,233 for "Phosphor-Converted White Light Emitting Diodes Having Narrow Band Green Phosphors," both of which are incorporated herein by reference in their entirety.

This application is incorporated by reference in its entirety in U.S. Patent Application Serial No. 15/591,629, filed May 10, 2017, and entitled "Phosphors With Narrow Green Emission."

Statement of Government Support

This invention was made with government support from the National Science Foundation under Grant No. 1534771 and the Department of Energy under Grant No. DE-EE0007622. The Federal Government has certain rights in this invention. This invention was also made with support from the Kentucky Economic Development Cabinet, Office of Entrepreneurship under grant agreement KSTC-184-512-17-247 from the Kentucky Science and Technology Corporation.

The following detailed description should be read with reference to the drawings, wherein like reference numerals refer to like elements throughout the different drawings. The drawings, which are not necessarily to scale, depict selected embodiments and are not intended to limit the scope of the invention. The detailed description illustrates the principles of the invention by way of example and not limitation. This description will clearly enable those skilled in the art to make and use the invention, and Several embodiments, modifications, variations, alternatives and uses of the invention are described. As used in this specification and claims, the term LED is intended to include light emitting diodes and semiconductor laser diodes.

Applicants have developed a new family of phosphors that can be excited by blue-emitting LEDs and emit narrow-band green light in response. These phosphors typically emit at a peak wavelength of about 500 nm to about 550 nm, with a FWHM of the peak of about 30 nm to about 50 nm. Examples of such phosphors are described later in this specification and in US Patent Application No. 15/591,629, entitled "Phosphors With Narrow Green Emission," which is referenced above.

In addition, Applicants have simulated the total emission spectrum from white-emitting phosphor-converted LEDs comprising a blue LED, a green phosphor excited by the blue LED, and a red phosphor excited by the blue LED. In these simulations, the blue LED had a peak emission at about 455nm and a FWHM of about 20nm. The green phosphor has a peak emission at about 500nm to about 550nm and a FWHM of about 30nm to about 50nm (as with applicant's various novel narrow green phosphors); in some cases, there may be 2 or more green phosphors A blend of slightly different phosphors. In some simulations, the red phosphor has a peak emission at about 630 nm and a FWHM of about 90 nm, which roughly corresponds to the emission from Intematix Corporation ER6436 red phosphor or Mitsubishi Chemical BR-102C. In other simulations, the red phosphor has a peak emission at about 626 nm and a FWHM of about 80 nm, which roughly corresponds to the emission from the Mitsubishi Chemical Corporation BR-102/Q red phosphor. No other light sources (eg, no additional LEDs or additional phosphors) would contribute to the total emission from the simulated device. However, in some embodiments, a white-emitting phosphor-converted LED as described in this specification may optionally include additional phosphors, eg, additional green-emitting phosphors and/or additional red-emitting phosphors.

In these simulations, the red phosphor peak and bandwidth were held constant, the LED emission peak and bandwidth were held constant, the green phosphor emission peak and bandwidth were varied, the ratio of green phosphor emission intensity to blue LED emission intensity was varied, and the red phosphor The ratio of volume emission intensity to blue LED emission intensity varies. (Changing the ratio of green and red phosphor emission intensities to blue LED emission intensities is similar to changing phosphor concentration and loading in phosphor converted LEDs).

The simulated spectrum was characterized by calculating various parameters including, for example, CCT, Duv (distance from the Planckian locus in the CIE chromaticity diagram), CRI, R9, R11, LER, and in the yellow region of the spectrum (e.g., about 550 nm to about 580 nm), which is measured as a percentage of the maximum intensity in the emission spectrum in the range of about 400 nm to about 700 nm.

Some exemplary results of these simulations and some related measurements are presented below.

CCT 2700K

Table 1A below characterizes three simulated spectra of a white-emitting phosphor-converted LED comprising a blue LED, an ER6436 red phosphor, and a green phosphor with peak emission at 524 nm, 528 nm, or 534 nm and a FWHM of 35 nm. body. The CCT of these spectra is between 2600 K and 2850 K, nominally 2700 K, and the CRI is greater than 90.

The trend for a green phosphor with a 35nm FWHM combined with a red phosphor with a FWHM of about 90nm appears to be that R11 has a maximum at the phosphor wavelength of 534nm. The R11 value then decreases as the peak wavelength decreases. R9 values tend not only to be extremely dependent on green phosphorescence Bulk peak wavelength, and depends on CCT and duv. For this particular combination of CCT and CRI, R9 appears to exhibit a relative maximum for the 522-524nm phosphor, with the highest value of 94 found for the 524nm peak green phosphor. For the peak at 532 to 522 nm, R9 increases with increasing CCT and to a lesser extent with decreasing duv. For the green phosphor with a peak at 534nm, when the CCT is about 2700K, R9 remains extremely constant across CCT and duv.

Table 1B below characterizes three simulated spectra of a white-emitting phosphor-converted LED comprising a blue LED, a BR102/Q red phosphor, and a chromatogram having a peak emission at 522nm, 526nm, or 532nm and a FWHM of 35nm. Green phosphor. The CCT of these spectra is between 2600 K and 2850 K, nominally 2700 K.

Narrower (about 80nm FWHM) and slightly blue-shifted (4nm) BR102/Q with slightly lower maxima achieves the expected results of CRI and R9 while increasing overall LER; moreover, the shift in the red phosphor spectrum makes it paired with The range of green phosphors to obtain the maximum value of R9, CRI and R11 varies. The various trends outlined above are similar to displaced red phosphors, but also displaced. For example, the largest R11 value was observed for a phosphor with a peak wavelength of 532 nm. The R9 trends outlined above also hold true with respect to changes to R9 with CCT and duv, none of the phosphor blends examined exhibited a relatively constant R9 as observed for 534nm green and ER6436.

Figure 2 shows the normalized results for a 2700 K LED for a 35nm FWHM with green phosphor emission peaking at 524nm (dotted line), 534nm (dashed line), and 528nm (solid line). Normalize the simulated spectrum.

Table 2 below characterizes three simulated spectra of a white-emitting phosphor-converted LED comprising a blue LED, an ER6436 red phosphor, and a green phosphor with peak emission at 520nm, 526nm, or 532nm and a FWHM of 40nm body. The CCT of these spectra is between 2600 K and 2850 K, nominally 2700 K, and the CRI is greater than 90.

The trend for green phosphors with 40nm FWHM appears to be that R11 has a maximum at the phosphor wavelength of 532nm. The R11 value then decreases as the peak wavelength shifts to 534 nm or decreases to 520 nm. R9 values tend to be extremely dependent not only on the green phosphor peak wavelength, but also on CCT and duv. For this particular combination of CCT and CRI, R9 appears to exhibit a relative maximum for the 520nm phosphor, with the highest being 96. For the peak from 534 to 520 nm, R9 increases with increasing CCT and to a lesser extent with decreasing duv.

Figure 3 shows the normalized simulated spectrum of a 2700 K LED for a 40nm FWHM with green phosphor emission peaking at 520nm (dotted line), 532nm (dashed line) and 526nm (solid line).

It is generally accepted that the CRI of white-emitting phosphor-converted LEDs increases as the color point of a particular phosphor blend moves below the CIE color space, typically characterized by a decrease in duv. 4A plots duv on the vertical axis versus CRI on the horizontal axis for simulated phosphor-converted LEDs comprising a blue LED, an ER6436 red phosphor, and a peak emission at 532 nm and a FWHM of 40 nm. The green phosphor. CCT of these spectra Between 2600 K and 2850 K, nominally 2700 K. This graph shows the expected trend of increasing CRI with decreasing duv over a CRI range of about 90 to about 94.

4B plots duv on the vertical axis versus CRI on the horizontal axis for simulated phosphor-converted LEDs comprising a blue LED, an ER6436 red phosphor, and a peak emission at 528 nm and a FWHM of 40 nm. The green phosphor. The CCT of these spectra is between 2600 K and 2850 K, nominally 2700 K. This graph shows a relatively consistent CRI of about 93 to about 94 across the entire range that would be considered "white light."

4C plots duv on the vertical axis versus CRI on the horizontal axis for simulated phosphor-converted LEDs comprising a blue LED, an ER6436 red phosphor, and a peak emission at 526 nm and a FWHM of 40 nm. The green phosphor. The CCT of these spectra is between 2600 K and 2850 K, nominally 2700 K. This graph also shows a relatively consistent CRI of about 93 to about 94 across the entire range that would be considered "white light."

Table 3 below characterizes three simulated spectra of a white-emitting phosphor-converted LED comprising a blue LED, an ER6436 red phosphor, and a green phosphor with peak emission at 518 nm, 524 nm, or 530 nm and a FWHM of 45 nm body. The CCT of these spectra is between 2600 K and 2850 K, nominally 2700 K, and the CRI is greater than 90.

The trend for green phosphors with a 45nm FWHM appears to be that R11 has a maximum at the phosphor wavelength of 530nm. The R11 value then decreases as the peak wavelength shifts to 532 nm or decreases to 518 nm. The R9 value tends not only to be extremely dependent on the green phosphor peak wave Long and depends on CCT and duv. For this particular combination of CCT and CRI, R9 appears to exhibit a relative maximum for the 518nm phosphor, with the highest being 96. For the peak from 532 to 518 nm, R9 increases with increasing CCT and to a lesser extent with decreasing duv.

Figure 5 shows the normalized simulated spectrum of a 2700 K LED for a 45nm FWHM with green phosphor emission peaking at 518nm (dotted line), 530nm (dashed line) and 524nm (solid line). .

Similar to the CRI versus duv trends discussed above for a simulated white-emitting phosphor-converted LED comprising a 40nm FWHM emission, a green phosphor comprising a peak emission at 530nm to 536nm and a 45nm FWHM exhibits a CRI range across 2700K 4 expected trends in the white area. For the green peak emission around 528nm, the CRI range starts to narrow, and for the phosphor at 526nm, the blend only establishes a CRI within 1 point across the white region. Once the peak emission wavelength of the green phosphor is reduced to 522nm, the blend exhibits a characteristic of CRI increasing with duv, and the CRI ranges approximately 3 points across the white region.

CCT 3000K

Table 4A below characterizes four simulated spectra of a white-emitting phosphor-converted LED comprising a blue LED, an ER6436 red phosphor, and a chromatogram having a peak emission at 514nm, 516nm, 518nm, or 520nm and a FWHM of 35nm. Green phosphor. The CCT of these spectra is between 2850 K and 3250 K, nominally 3000 K, and the CRI is greater than 80.

Table 4B below characterizes the simulated spectrum of a white-emitting phosphor-converted LED comprising a blue LED with a peak emission at 457 nm and a FWHM of 21 nm, a BR102/Q red phosphor, and a peak emission at 517 nm And the green phosphor of FWHM of 36nm. The CCT of this spectrum is between 2850 K and 3250 K, nominally 3000 K.

Table 4C below characterizes the measured spectrum of an example white-emitting phosphor-converted LED (Sample No. JM388F9-28ma) comprising a blue LED, BR102/ Q red phosphor and green phosphor with peak emission at 517 nm and FWHM of 36 nm (sample KB3-170-545). The CCT of this spectrum is between 2850 K and 3250 K, nominally 3000 K.

The trend for green phosphors with a 35nm FWHM appears to be that R11 has a maximum at the phosphor wavelength of 520nm. The R11 value then decreases as the peak wavelength decreases. R9 values tend to be extremely dependent not only on the green phosphor peak wavelength, but also on CCT and duv. For the peak from 520 to 516 nm, R9 increases with increasing duv and with decreasing CCT. For the green phosphor with a peak at 514nm, when the CCT is about 3000K, R9 remains extremely constant across CCT and duv. The highest R9 values (R9>90) were obtained with phosphors peaking at 520nm and some with 518nm.

Figure 6 shows the normalized simulated spectra of a 3000 K LED for a 35nm FWHM with green phosphor emission peaking at 514nm (dashed line), 516nm (dashed line), 518nm (dashed line) and 520nm (solid line). .

Figure 7 shows the simulated spectrum (solid line) of a 3000 K LED for green phosphor emission with a 36nm FWHM peaking at 517nm and the measured spectrum (dashed line) of the example phosphor-converted LED characterized in Table 4C.

Table 5A below characterizes the simulated spectrum of a white-emitting phosphor-converted LED comprising a blue LED, ER6436 red phosphor, and a green phosphor with peak emission at 522 nm and a FWHM of 40 nm. A green phosphor with these spectral characteristics has been prepared as sample number YBG170620-1 (521-41). The CCT of this spectrum is between 2850 K and 3250 K, nominally 3000 K, and the CRI is greater than 90.

Table 5B below characterizes the simulated spectrum of a white-emitting phosphor-converted LED comprising a blue LED, ER6436 red phosphor, and a green phosphor with peak emission at 530 nm and a FWHM of 40 nm. A green phosphor with these spectral characteristics has been prepared as sample number KB3-123-486(530-39). The CCT of this spectrum is between 2850 K and 3250 K, nominally 3000 K.

Table 5C below characterizes the simulated spectrum of a white-emitting phosphor-converted LED comprising a blue LED, ER6436 red phosphor, and a green phosphor with a peak emission at 534 nm and a FWHM of 40 nm. A green phosphor with these spectral characteristics has been prepared as sample number ELT-069(533-41). The CCT of this spectrum is between 2850 K and 3250 K, nominally 3000 K.

The trend for green phosphors with 40nm FWHM appears to be that R11 has a maximum at the phosphor wavelength of 532nm. The R11 value then decreases as the peak wavelength increases to 534 nm or decreases to 522 nm. The R9 value tends not only to be extremely dependent on the green phosphor peak wave Long and depends on CCT and duv. For the peak at 534 to 524 nm, R9 decreases with duv and increases with CCT. For the green phosphor with a peak at 522nm, when the CCT is about 3000 K, R9 remains extremely constant during CCT and duv changes, and correspondingly some of the highest R9 values are obtained (R9>95).

Figure 8 shows the normalized simulated spectrum of a 3000 K LED for a 40nm FWHM with green phosphor emission peaking at 522nm (dotted line), 530nm (dashed line) and 534nm (solid line).

9A plots duv on the vertical axis versus CRI on the horizontal axis for simulated phosphor-converted LEDs comprising a blue LED, an ER6436 red phosphor, and a green phosphor with peak emission at 530 nm. . Across most of the white range, the CRI ranges from 92 to 94, which increases as duv decreases.

9B plots duv on the vertical axis versus CRI on the horizontal axis for simulated phosphor-converted LEDs comprising a blue LED, an ER6436 red phosphor, and a green phosphor with peak emission at 528 nm . The CRI is very stable with a range of only about 1 point in the entire white area at 3000K.

9C plots duv on the vertical axis versus CRI on the horizontal axis for simulated phosphor-converted LEDs comprising a blue LED, an ER6436 red phosphor, and a green phosphor with peak emission at 526 nm . This graph shows a strict grouping of CRI values, similar to the grouping in Figure 9B.

Figure 9D plots duv on the vertical axis versus CRI on the horizontal axis for simulated phosphor-converted LEDs comprising a blue LED, an ER6436 red phosphor, and a green phosphor with peak emission at 522 nm . In this graph, CRI increases as duv increases.

Table 6A below characterizes two simulated spectra of a white-emitting phosphor-converted LED comprising a blue LED, an ER6436 red phosphor, and a green phosphor with peak emission at 520nm or 524nm and a FWHM of 45nm. The CCT of these spectra is between 2850 K and 3250 K, nominally 3000 K, and the CRI is greater than 90.

Table 6B below characterizes the simulated spectrum of a white-emitting phosphor-converted LED comprising a blue LED, ER6436 red phosphor, and a green phosphor with peak emission at 530 nm and a FWHM of 45 nm. Green phosphors with these spectral characteristics have been prepared as sample numbers ELT047C (531-45) and YBG 170403-4B (530-44). The CCT of these spectra is between 2850 K and 3250 K, nominally 3000 K.

The trend here seems to be that R11 is at a maximum at the phosphor wavelengths of 530 and 532 nm. The R11 value then decreases as the peak wavelength increases to 534 nm or decreases to 518 nm. R9 values tend to be extremely dependent not only on the green phosphor peak wavelength, but also on CCT and duv. For the peak at 532 to 524 nm, R9 decreases with duv and increases with CCT. For the green phosphors with peaks at 522 and 520 nm, when the CCT is about 3000 K, R9 remains extremely constant during CCT and duv changes, and correspondingly some of the highest R9 values are obtained (R9>95).

Figure 10 shows the normalized simulated spectrum of a 3000 K LED for a 45nm FWHM with green phosphor emission peaking at 520nm (dotted line), 524nm (dashed line), and 530nm (solid line).

CCT 3500K

Table 7A below characterizes three simulated spectra of a white-emitting phosphor-converted LED comprising a blue LED, an ER6436 red phosphor, and a green phosphor with peak emission at 516 nm, 518 nm, or 520 nm and a FWHM of 35 nm. body. The CCT of these spectra is between 3250 K and 3750 K, nominally 3500 K, and the CRI is greater than 80.

Table 7B below characterizes the simulated spectrum of a white-emitting phosphor-converted LED comprising a blue LED with a peak emission at 457 nm and a FWHM of 21 nm, a BR102/Q red phosphor, and a peak emission at 517 nm And the green phosphor of FWHM of 36nm. The CCT of these spectra is between 3250 K and 3750 K, nominally 3500 K.

Table 7C below characterizes the measured spectrum of an example white-emitting phosphor-converted LED (sample JM388-E3-59) comprising a blue LED, BR102, with a peak emission at 457 nm and a FWHM of 21 nm. /Q red phosphor and has 517 Green phosphor with peak emission at nm and FWHM of 36 nm. The CCT of this spectrum is between 3250 K and 3750 K, nominally 3500 K.

As can be seen in Table 8 below, for example, the trend here appears to be that R9 increases with distance above the Planckian locus, and R9 increases with decreasing CCT. For phosphors between 516nm and 520nm peak wavelengths, there is a clear trend of increasing R11 and increasing phosphor wavelength. Table 8 reports the R9 values for selected CCT and duv for the simulated spectrum of a white-emitting phosphor-converted LED comprising a blue LED, an ER6436 red phosphor, and a peak emission at 520 nm and a FWHM of 35 nm. Green phosphor.

Figure 11 shows the normalized simulated spectrum of a 3500 K LED for green phosphor emission with a 35nm FWHM peaking at 520nm (dotted line), 518nm (solid line) and 516nm (dashed line).

Figure 12 shows the simulated spectrum (solid line) of a 3500 K LED for green phosphor emission with a 36nm FWHM peaking at 517nm and the example phosphor conversion characterized in Table 7C. The measured spectrum (dashed line) of the LED was changed.

Table 9 below characterizes three simulated spectra of a white-emitting phosphor-converted LED comprising a blue LED, an ER6436 red phosphor, and a green phosphor with peak emission at 524 nm, 528 nm, or 532 nm and a FWHM of 40 nm body. The CCT of these spectra is between 3250 K and 3750 K, nominally 3500 K, and the CRI is greater than 90.

The trends here seem to be for R9 to increase with distance above the Planckian locus, and R9 to increase with decreasing CCT. For this particular combination of CCT and CRI, R9 appears to exhibit a relative maximum for the 528nm phosphor. For phosphors between 524nm and 532nm peak wavelengths, there is a clear trend of increasing R11 and increasing phosphor wavelength. CRI versus duv follows the expected trend: For phosphors with longer wavelengths, such as 540 to 532 nm, the CRI increases with decreasing duv over a range of 4 points across the region that is generally considered white. The CRI range compresses down to about 2 and shows no real correlation with the duv of the phosphors with peak wavelengths of 526 and 528 nm. Shorter wavelength phosphors exhibit a wider range of CRI, but have the opposite trend of CRI increasing with duv.

Figure 13 shows the normalized simulated spectrum of a 3500 K LED for green phosphor emission with a 40nm FWHM peaking at 532nm (dotted line), 528nm (solid line) and 524nm (dashed line).

Table 10 below characterizes three simulated spectra of a white-emitting phosphor-converted LED comprising a blue LED, an ER6436 red phosphor, and a 530nm, Green phosphor with peak emission at 526nm or 522nm and FWHM of 45nm. The CCT of these spectra is between 3250 K and 3750 K, nominally 3500 K, and the CRI is greater than 90.

The trends here seem to be for R9 to increase with distance above the Planckian locus, and R9 to increase with decreasing CCT. For this particular combination of CCT and CRI, R9 appears to exhibit a relative maximum for the 526nm phosphor. For phosphors between 522nm and 532nm peak wavelengths and a slight relative maximum for the phosphor with a 530nm peak wavelength, there is a clear trend of increasing R11 and increasing phosphor wavelength.

Figure 14 shows the normalized simulated spectrum of a 3500 K LED for green phosphor emission with a 45nm FWHM peaking at 530nm (dotted line), 526nm (solid line) and 522nm (dashed line).

Figure 15 plots on the horizontal axis CRI and R9 and green phosphor emission peak wavelengths for simulated white phosphor-converted LEDs including blue LEDs, ER6436 red phosphor, and narrow green phosphor. The CCT of these simulated devices is nominally 3000 K and the duv is +0.003. FWHM variation of green phosphor emission. This graph shows that using lower peak wavelength green phosphors results in higher R9 values.

Figure 16 plots CRI versus duv for simulated white phosphor-converted LEDs comprising a blue LED, ER6436 red phosphor, and a narrow green phosphor with a peak wavelength of 532 nm and varying FWHM. The CCT of these analog devices is nominally 3000K. This graph shows that at this wavelength for the green phosphor, the CRI roughly increases with duv decreases and increases. This trend follows a generally recognized trend. Furthermore, the graph shows that the range of obtained CRI values decreases with decreasing FWHM.

Figure 17 plots CRI versus duv for simulated white phosphor-converted LEDs comprising a blue LED, ER6436 red phosphor, and a narrow green phosphor with a peak wavelength of 522 nm and varying FWHM. The CCT of these analog devices is nominally 3000K. This graph shows that at this wavelength for the green phosphor, CRI generally increases with increasing duv. This trend is opposite to the generally accepted trend, where CRI generally decreases with increasing duv. Furthermore, the graph shows that the range of obtained CRI values decreases with decreasing FWHM.

Table 11 below characterizes several simulated spectra of a white-emitting phosphor-converted LED comprising a red phosphor with a peak emission wavelength between 450 nm and 470 nm, with a nominal peak wavelength of 620 nm and a FWHM of 90 nm, and Green phosphor with peak emission between 508nm and 534nm and FWHM between 40nm and 50nm. The CCT of these spectra is between 2850 K and 3250 K, nominally 3000 K.

Table 12 below characterizes certain simulated spectra of a white-emitting phosphor-converted LED comprising a red phosphor with a peak emission wavelength between 430 nm and 455 nm, with a nominal peak wavelength of 620 nm and a FWHM of 90 nm, and Green phosphor with peak emission between 504nm and 524nm and FWHM between 35nm and 50nm. The CCT of these spectra is between 3750 K and 4250 K, nominally 4000 K.

Table 13 below shows the properties of commercially available LEDs purchased and tested by applicants. and so on The LEDs utilize yellow-green phosphors that are significantly broader than those disclosed herein, and thus do not exhibit valleys in the emission spectrum.

Example Narrow Green Phosphor

KB3-170-545, 517nm peak, 36nm FWHM. 0.523g Eu, 0.106g CaS, _{0.886g Al2S3} , _{0.174g Ga2S3} , 0.110g S and 0.090g _AlCl3 were ground and then divided into 4 vacuum-sealed quartz thimbles. The jacket was heated together to 400°C for one hour, and then the temperature was increased to 900°C and held for 6 hours. Cool the boiler at 50°C per hour. The sleeves were opened under an inert atmosphere and ground together to combine them.

KB3-163-537, 527nm peak, 41nm FWHM. 0.562g Eu, 0.446g _Al2S3 , 0.412g _Ga2S3 , 0.112g S and _{0.075g AlCl3} were _ground and then divided into 4 vacuum-sealed quartz thimbles. The jacket was heated together to 400°C for one hour, and then the temperature was increased to 900°C and held for 6 hours. Cool the boiler at 50°C per hour. The cannula was opened under an inert atmosphere and its contents were milled together to combine them.

KB3-117-475a, 529nm peak, 41nm FWHM. 0.225 g Eu, 0.166 g Al ₂ S ₃ , 0.209 g Ga ₂ S ₃ , 0.020 g S and 0.045 g AlCl ₃ were ground and then divided into 2 vacuum-sealed quartz thimbles. One of the thimbles was heated to 400°C for one hour, and then the temperature was increased to 900°C and held for 6 hours. Cool the boiler at 50°C per hour.

KB3-123-486, 530nm peak, 39nm FWHM. 0.562 g Eu, 0.416 g Al ₂ S ₃ , 0.522 g Ga ₂ S ₃ , 0.050 g S, and 0.115 g AlCl ₃ were ground and then divided into 4 vacuum-sealed quartz thimbles. The jacket was heated together to 400°C for one hour, and then the temperature was increased to 900°C and held for 6 hours. Cool the boiler at 50°C per hour. The cannula was opened under an inert atmosphere and its contents were milled together to combine them.

KB3-117-476a, 539nm peak, 42nm FWHM. 0.215 g Eu, 0.115 g Al ₂ S ₃ , 0.270 g Ga ₂ S ₃ , 0.020 g S and 0.045 g AlCl ₃ were ground and then divided into 2 vacuum-sealed quartz thimbles. One of the thimbles was heated to 400°C for one hour, and then the temperature was increased to 900°C and held for 6 hours. Cool the boiler at 50°C per hour.

KB3-080-430, 528nm peak, 47nm FWHM. 0.006g Mg, 0.113g SrS, 0.010g Eu, 0.023g Al, _{0.198g Ga2S3} and 0.071g S were ground and placed in a quartz thimble and vacuum sealed. The samples were heated together to 400°C for 6 hours, and then the temperature was increased to 800°C and held for 12 hours. Cool the boiler within 6 hours. The samples were opened under an inert atmosphere, ground and sealed in new quartz sleeves. It was heated to 950°C for 24 hours and cooled to room temperature over 6 hours.

KB3-121-481, 533nm peak, 44nm FWHM. 0.117 g Eu, 0.048 g Al ₂ S ₃ , 0.114 g Ga ₂ S ₃ , 0.031 g S, and 0.023 g AlCl ₃ were ground and then vacuum sealed in a quartz sleeve. The sample was heated to 400°C for one hour, and then the temperature was increased to 850°C and held for 6 hours. Cool the boiler at 25°C per hour.

YBG170620-1, 521nm peak, 41nm FWHM. The stoichiometric Eu, Al, _Ga2S3 and _{15 wt} % excess S to form Eu( _Al1.85Ga0.26 ) _S4.37 were thoroughly ground in a mortar and pestle in a glove box and vacuum sealed in a quartz sleeve middle. The mixture was placed in dry silica sleeves that were evacuated and sealed at a length of approximately 5 inches. The reaction was carried out in a box boiler. The temperature was raised to 400°C and held for 2 hours, and again to 900°C and held for 8 to 12 hours, followed by cooling to room temperature for 6 hours.

ELTEAGS-012-B-2, 516nm peak, 36nm FWHM. The reagents CaS, Eu, Al and S were combined stoichiometrically to obtain a nominal composition CaAl _2.7 S _5.05 : 8.5% Eu and charged into an alumina crucible in a horizontal tube furnace. After a 30 min purge with Ar, the mixture was heated to 400°C, at which point _H2S gas flow was started. After 1 hour at 400°C, the boiler was heated to 1000°C for 2 hours. After cooling, the _H2S gas was turned off and the product was cooled to room temperature under flowing Ar.

ELTA 1S-067-B, 516nm peak, 35nm FWHM. Eu(Al _1-x Ga _x ) _2.7 S _5.05+y was prepared by combining Eu, Al ₂ S ₃ , Ga ₂ S ₃ and S in a stoichiometric ratio. 3 wt% AlCl ₃ and 10 mg excess S were added before combustion. The mixture was sealed in an evacuated silica thimble and heated to 400°C for 2 hours, then to 850°C for 6 hours. The sample was cooled to room temperature at a rate of 50°C/h.

ELTA 1S-073, 520nm peak, 36nm FWHM. CaS, Eu, Al and S are combined stoichiometrically to obtain a nominal composition CaAl _2.7 S _5.05 : 8.5%Eu. The mixture was homogenized under Ar with a mortar and pestle, then packed into a silica-carbide thimble which was then evacuated and vacuum-sealed. The synthesis was carried out by a stepwise heating method: 290°C (17h), 770°C (24h), 870°C (24h) and slow cooling over 20h. The product was recovered and manually reground and heated to 400°C (6h) and 1000°C (3h) before being returned to a new silica-carbonite sleeve.

ELTEAGS-013-A-2, 520nm peak, 40nm FWHM. CaS, EuF ₃ , Al, Ga ₂ S ₃ and S were combined stoichiometrically to obtain the target composition CaAl _2.565 Ga _0.135 S _5.05 : 8.5%Eu(5%Ga). The samples were homogenized under Ar, then loaded into alumina crucibles and placed in a horizontal tube furnace. After purging with flowing Ar for 30 min, the mixture was heated to 400 °C, at which time _H2S gas flow was started. After being held at 400°C for 1 hour, the sample was heated to 1000°C for 2 hours. The _H2S gas was turned off at 800°C during cooling to room temperature over 2 hours.

ELTEAGS-016-A-2, 522nm peak, 39nm FWHM. CaAl _2.43 Ga _0.27 S _5.05 : 8.5% Eu was prepared from stoichiometric CaS, EuF ₃ , Al, Ga ₂ S ₃ and S under flowing H ₂ S/Ar. The samples were homogenized under Ar atmosphere, then loaded into alumina crucibles and placed in a horizontal tube furnace. After purging with flowing Ar for 1 h, the mixture was heated to 400 °C for 1 h at which time _H2S gas flow was started. The samples were then heated to 1000°C for 2 hours and cooled to room temperature. The _H2S gas was turned off at 800°C during cooling.

ELTA 1S-035-G, 33nm peak, 1nm FWHM. _EuAlGaS4 was prepared by stoichiometrically _{combining Eu} , _Al2S3 , _Ga2S3 and S under Ar. The mixture was sealed in an evacuated quartz sleeve and heated to 400°C (6h), then to 800°C (12h). After trituration of the product and addition of 50 mg excess S, the second heat treatment was followed by heating to 400° C. (6 h), followed by heating to 1000° C. (6 h).

ELTA 1S-069, 533nm peak, 41nm FWHM. The reagents Eu, Al ₂ S ₃ , Ga ₂ S ₃ and S were combined stoichiometrically to produce EuAl _1.35 Ga _1.35 S _5.05 . Homogenization of the mixture was performed with a mortar and pestle under Ar atmosphere. 3 wt% _AlCl3 was used as flux and the samples were sealed in evacuated quartz sleeves. The reaction was carried out by heating the quartz ampoule to 400 °C (1 h) and then to 900 °C (6 h). The product was recovered and ground manually with a mortar and pestle.

ELTA 1S-036-F, 528nm peak, 45nm FWHM. EuAl _0.9 Ga _1.1 S ₄ was synthesized from stoichiometric Eu, Al ₂ S ₃ , Ga metal and S. The reactants were mixed under Ar and then sealed in an evacuated quartz tube. The final product is obtained after two heat treatments. Heat 1: 400°C (12h), 800°C (12h). Heat 2: 400°C (12h), 1000°C (6h). Samples were reground with 50 mg excess S and sealed in evacuated quartz sleeves during intermediate steps.

ELTA 1S-036-E, 534nm peak, 45nm FWHM. EuAl _0.8 Ga _1.2 S ₄ was synthesized from stoichiometric Eu, Al ₂ S ₃ , Ga metal and S. The reactants were mixed under Ar and sealed in an evacuated quartz tube. The final product is obtained after two heat treatments. Heat 1: 400°C (12h), 800°C (12h). Heat 2: 400°C (12h), 1000°C (6h). Samples were reground with 50 mg excess S and sealed in evacuated quartz sleeves during intermediate steps.

ELTA 1S-042E and F, 536nm peak, 45nm FWHM. Eu(Al _0.4 Ga _0.6 ) ₂ S ₄ was synthesized from a stoichiometric pre-combustion mixture of Eu, Al ₂ S ₃ , Ga ₂ S ₃ and S. The product was combined with 0.12 g _I2 (15 wt%) and 0.16 g S (20 wt%) before being divided into two parts and sealed into two evacuated quartz sleeves. Both samples were heated to 950°C (2h) and subsequently quenched in air or water.

ELTA 1S-037-B, 50nm peak, 51nm FWHM. CaAl _0.675 Ga _2.025 S _5.05 : 8.5% Eu was synthesized by combining CaS, Eu, Al ₂ S ₃ , Ga ₂ S ₃ and S stoichiometrically. The mixture was homogenized under Ar using a mortar and pestle, then packed into a silica-carbide thimble which was then evacuated and vacuum-sealed. Synthesis was carried out by a stepwise heating method: 290°C (17h), 770°C (24h), 870°C (24h) and cooling to room temperature over 9h. The product was recovered and manually reground with 50 mg S and heated to 400°C (6h) and 1000°C (3h) before adding to another silica-carbon-coated thimble.

The phosphor paste is formed by combining Dow Corning OE-65502 part silicone, red phosphor BR102/Q and green phosphor such as KB3-163-537. A portion of this paste was used to fabricate phosphor converted LEDs and applied to 2835 from Power Opto Co. PLCC packaging; cure the silicone overnight at approximately 100°C.

Various embodiments are described in the following numbered clauses.

Clause 1. A light emitting device comprising: a semiconductor light source emitting blue light; a first phosphor arranged to be excited by the blue light emitted by the semiconductor light source and emitting a peak emission having a peak emission at about 500 nm to about 550 nm and about Green light having a full width at half maximum of 30nm to about 50nm in response; and a second phosphor arranged to be excited by blue light emitted by the semiconductor light source and emitting having a peak emission at a wavelength less than or equal to about 635nm Red light in response; wherein the bulk emission spectrum from the light emitting device has a dip between about 550 nm and about 580 nm, and the minimum intensity in the dip is greater than or equal to in the bulk emission spectrum in the range of about 400 nm to about 700 nm About 25% and less than or equal to about 75% of its maximum strength.

Clause 2. The light emitting device of Clause 1, wherein the minimum value from the overall emission spectrum of the light emitting device between about 550 nm and about 580 nm has a minimum intensity that is greater than or equal to about 30%, greater than or equal to about 35%, greater than or equal to about 40%, greater than or equal to about 45%, greater than or equal to about 50%, greater than or equal to about 55%, greater than or equal to about 60%, or greater than or equal to 65% in the range of about 400nm to about 700nm The maximum intensity in the overall emission spectrum of .

Item 3. The light emitting device of Item 1 or Item 2, wherein the blue light emitted by the semiconductor light source has a peak at about 430 nm to about 465 nm and a full width at half maximum of about 10 nm to about 35 nm.

Clause 4. The light emitting device according to any one of clauses 1 to 3, wherein the green light emitted by the first phosphor has a full width at half maximum which is less than or equal to about 45 nm, less than or equal to about 40 nm nm, or less than or equal to about 35 nm.

Clause 5. The light emitting device of any one of clauses 1 to 4, wherein the red light emitted by the second phosphor has a full width at half maximum of about 70 nm to about 100 nm.

Clause 6. The light emitting device of any one of Clauses 1 to 5, wherein the overall emission spectrum from the light emitting device has about 40 or more, about 50 or more, about 60 or more, about 70 or more, about 70 or more, Or an R9 color rendering value of about 80, greater than or equal to about 90, or greater than or equal to about 95.

Clause 7. The light emitting device of any one of clauses 1 to 6, wherein the overall emission spectrum from the light emitting device has a value of about 80 or greater, about 85 or greater, about 90 or greater, or about 95 or greater CRI.

Clause 8. The light emitting device of any one of clauses 1 to 7, wherein the overall emission spectrum from the light emitting device has a radiant luminous efficacy of greater than or equal to about 280.

Clause 9. The light emitting device of any one of Clauses 1 to 8, wherein the overall emission spectrum from the light emitting device has an R9 color rendering value of about 50 or greater and a radiant luminous efficacy of about 300 or more.

Clause 10. The light emitting device of any one of clauses 1 to 9, wherein the light emitting device does not comprise a phosphor that emits light having a peak emission greater than or equal to about 635 nm.

Clause 11. The light emitting device of Clause 1, wherein: the first phosphor emits green light having a peak emission at about 500 nm to about 540 nm; and the overall emission spectrum from the light emitting device has an R9 color rendering value of greater than or equal to about 40 .

Clause 12. The light emitting device of Clause 11, wherein the first phosphor emits green light having a peak emission at about 520 nm to about 540 nm.

Clause 13. The light emitting device of clause 11 or clause 12, wherein the minimum value of the overall emission spectrum from the light emitting device between about 550 nm and about 580 nm has a minimum intensity that is greater than or equal to about 30%, greater than or equal to about 35% %, greater than or equal to about 40%, greater than or equal to about 45%, greater than or equal to about 50%, greater than or equal to about 55%, greater than or equal to about 60%, or greater than or equal to 65% at about 400nm to about 700nm The maximum intensity in the overall emission spectrum within the range.

Item 14. The light emitting device of any one of Items 11 to 13, wherein the blue light emitted by the semiconductor light source has a peak at about 430 nm to about 465 nm and a full width at half maximum of about 10 nm to about 35 nm.

Clause 15. The light emitting device of any one of clauses 11 to 14, wherein the green light emitted by the first phosphor has a full width at half maximum of less than or equal to about 45 nm, less than or equal to about 40 nm, or less than or equal to about 35 nm.

Clause 16. The light emitting device of any one of Clauses 11 to 15, wherein the red light emitted by the second phosphor has a full width at half maximum of about 70 nm to about 100 nm.

Clause 17. The light emitting device of any one of clauses 11 to 16, wherein the overall emission spectrum from the light emitting device has about 50 or more, about 60 or more, about 70 or more, about 80 or more, about 80 or more, Or an R9 color rendering value equal to about 90, or greater than or equal to about 95.

Clause 18. The light emitting device of any one of clauses 11 to 17, wherein the overall emission spectrum from the light emitting device has a value of about 80 or greater, about 85 or greater, about 90 or greater, or about 95 or greater CRI.

Clause 19. The light emitting device of any one of clauses 11 to 18, wherein the overall emission spectrum from the light emitting device has a radiant luminous efficacy of greater than or equal to about 280.

Clause 20. The light emitting device of any one of Clauses 11 to 19, wherein the overall emission spectrum from the light emitting device has an R9 color rendering value of about 50 or greater and a radiant luminous efficacy of about 300 or more.

Clause 21. The light emitting device of any one of clauses 11 to 20, wherein the light emitting device does not comprise a phosphor that emits light having a peak emission greater than or equal to about 635 nm.

Clause 22. The light emitting device of Clause 1, wherein: the first phosphor emits green light with a peak emission at about 500 nm to about 540 nm; the second phosphor emits green light with a peak emission less than or equal to about 620 nm; and The overall emission spectrum from the light emitting device has an R9 color rendering value greater than or equal to about zero.

Clause 23. The light emitting device of Clause 22, wherein a minimum of the overall emission spectrum from the light emitting device between about 550 nm and about 580 nm has a minimum intensity that is greater than or equal to about 30%, greater than or equal to about 35%, greater than or equal to about 40%, greater than or equal to about 45%, greater than or equal to about 50%, greater than or equal to about 55%, greater than or equal to about 60%, or greater than or equal to 65% in the range of about 400nm to about 700nm The maximum intensity in the overall emission spectrum of .

Item 24. The light emitting device of Item 22 or Item 23, wherein the blue light emitted by the semiconductor light source has a peak at about 430 nm to about 465 nm and a full width at half maximum of about 10 nm to about 35 nm.

Clause 25. The light emitting device of any one of clauses 22 to 24, wherein the green light emitted by the first phosphor has a full width at half maximum of less than or equal to about 45 nm, less than or equal to about 40 nm, or less than or equal to about 35 nm.

Clause 26. The light emitting device of any one of clauses 22 to 25, wherein the red light emitted by the second phosphor has a full width at half maximum of about 70 nm to about 100 nm.

Clause 27. The light emitting device of any one of clauses 22 to 26, wherein the overall emission spectrum from the light emitting device has about 10 or more, about 20 or more, about 30 or more, about 40 or more, An R9 color rendering value of about 50 or greater, about 60 or greater, about 70 or greater, about 80 or greater, about 90 or greater, or 95 or greater.

Clause 28. The light emitting device of any one of clauses 22 to 27, wherein the overall emission spectrum from the light emitting device has a value of about 80 or greater, about 85 or greater, about 90 or greater, or about 95 or greater. CRI.

Clause 29. The light emitting device of any one of clauses 22 to 28, wherein the overall emission spectrum from the light emitting device has a radiative luminous efficacy of greater than or equal to about 280.

Clause 30. The light emitting device of any one of clauses 22 to 29, wherein the overall emission spectrum from the light emitting device has an R9 color rendering value of about 50 or greater and a radiant luminous efficacy of about 300 or more.

Clause 31. The light emitting device of any one of clauses 22 to 30, wherein the light emitting device does not comprise a phosphor that emits light having a peak emission greater than or equal to about 635 nm.

Clause 32. The light emitting device of any one of clauses 1 to 31, wherein the first phosphor does not comprise quantum dots, or the second phosphor does not comprise quantum dots, or the first phosphor does not comprise quantum dots and the second phosphor The body does not contain quantum dots.

Clause 33. The light emitting device of any one of Clauses 1 to 31, wherein the first phosphor comprises quantum dots, or the second phosphor comprises quantum dots, or the first phosphor and the second phosphor comprise quantum dots.

Clause 34. The light emitting device according to any one of clauses 1 to 31, wherein the first phosphorescent system is arranged directly on the semiconductor light source.

Clause 35. The light emitting device of any one of clauses 1 to 34, wherein the light emitting device does not comprise a filter that creates a recess between about 550nm and about 580nm or about 590nm.

The present invention is illustrative and not limiting. Further modifications in view of the present invention will be apparent to those skilled in the art and are intended to be within the scope of the appended claims. For example, a light emitting device as described herein can optionally include quantum dots that emit in the green or red portion of the visible spectrum. Quantum dots that may be suitable for such applications include, for example, quantum dots with a cadmium selenide core and a cadmium sulfide and zinc sulfide shell, and quantum dots with an indium phosphide core and a zinc sulfide shell. The emission peak wavelength is mainly determined by the size of the quantum dots. For cadmium selenide, a diameter of about 2.5 nm produces green emission, while a diameter of about 6 nm produces red emission (see e.g. http://www.nn-labs.com/wp-content/uploads/2017/06/ CSE-Tech-Specs.pdf). For indium phosphide, a diameter of about 7 nm yields green-emitting quantum dots, while a diameter of about 15 nm yields red-emitting quantum dots (see e.g. Journal of Nanomaterials vol. 2012, article ID 869284, page 11 doi: 10.1155/2012 /869284).

Claims (30)

A light emitting device comprising: a semiconductor light source emitting blue light; a first phosphor arranged to be excited by the blue light emitted by the semiconductor light source, and emit a peak emission having a peak emission of about 500 nm to about 550 nm and about Green light having a full width at half maximum of 30 nm to about 50 nm in response; and a second phosphor arranged to be excited by the blue light emitted by the semiconductor light source and emit light having a wavelength less than or equal to about 635 nm peak emitted red light in response; wherein the overall emission spectrum from the light emitting device has a dip between about 550 nm and about 580 nm, and the minimum intensity in the dip is greater than or equal to between about 400 nm to about 700 nm About 25% and less than or equal to about 75% of the maximum intensity in the overall emission spectrum within the range. The light emitting device according to claim 1, wherein the blue light emitted by the semiconductor light source has a peak value at about 430 nm to about 465 nm and a full width at half maximum of about 10 nm to about 35 nm. The light emitting device of claim 1, wherein the green light emitted by the first phosphor has a full width at half maximum of less than or equal to about 45 nm. The light emitting device according to claim 1, wherein the red light emitted by the second phosphor has a full width at half maximum of about 70 nm to about 100 nm. The light emitting device of claim 1, wherein the overall emission spectrum from the light emitting device has an R9 color rendering value of greater than or equal to about 40. The light emitting device of claim 1, wherein the overall emission spectrum from the light emitting device has a CRI of about 80 or greater. The light emitting device of claim 1, wherein the overall emission spectrum from the light emitting device has a radiant luminous efficacy of greater than or equal to about 280. The light emitting device of claim 1, wherein the overall emission spectrum from the light emitting device has an R9 color rendering value of greater than or equal to about 50 and a radiation luminous efficacy of greater than or equal to about 300. The light emitting device of claim 1, wherein the light emitting device does not comprise phosphors that emit light having a peak emission greater than or equal to about 635 nm. The light emitting device of claim 1, wherein: the first phosphor emits green light having a peak emission at about 500 nm to about 540 nm; and the overall emission spectrum from the light emitting device has an R9 of greater than or equal to about 40 Color value. The light emitting device of claim 10, wherein the first phosphor emits green light having a peak emission at about 520 nm to about 540 nm. The light emitting device according to claim 10, wherein the blue light emitted by the semiconductor light source has a peak at about 430 nm to about 465 nm and a full width at half maximum of about 10 nm to about 35 nm. The light emitting device of claim 10, wherein the green light emitted by the first phosphor has a full width at half maximum of less than or equal to about 45 nm. The light emitting device according to claim 10, wherein the red light emitted by the second phosphor has a full width at half maximum of about 70 nm to about 100 nm. The light emitting device of claim 10, wherein the overall emission spectrum from the light emitting device has a CRI of about 80 or greater. The light emitting device of claim 10, wherein the overall emission spectrum from the light emitting device has a radiant luminous efficacy of greater than or equal to about 280. The light emitting device of claim 10, wherein the overall emission spectrum from the light emitting device has an R9 color rendering value of greater than or equal to about 50 and a radiation luminous efficacy of greater than or equal to about 300. The light emitting device of claim 10, wherein the light emitting device does not comprise a phosphor that emits light having a peak emission greater than or equal to about 635 nm. The light emitting device of claim 1, wherein the first phosphor emits green light having a peak emission at about 500 nm to about 540 nm; the second phosphor emits green light having a peak emission less than or equal to about 620 nm and the overall emission spectrum from the light emitting device has an R9 color rendering value greater than or equal to about zero. The light emitting device according to claim 19, wherein the blue light emitted by the semiconductor light source has a peak at about 430 nm to about 465 nm and a full width at half maximum of about 10 nm to about 35 nm. The light emitting device of claim 19, wherein the green light emitted by the first phosphor has a full width at half maximum of less than or equal to about 45 nm. The light emitting device according to claim 19, wherein the red light emitted by the second phosphor has a full width at half maximum of about 70 nm to about 100 nm. The light emitting device of claim 19, wherein the overall emission spectrum from the light emitting device has a CRI of about 80 or greater. The light emitting device of claim 19, wherein the overall emission spectrum from the light emitting device has a radiant luminous efficacy of greater than or equal to about 280. The light emitting device of claim 19, wherein the overall emission spectrum from the light emitting device has an R9 color rendering value of greater than or equal to about 50 and a radiation luminous efficacy of greater than or equal to about 300. The light emitting device of claim 19, wherein the light emitting device does not comprise phosphors that emit light having a peak emission greater than or equal to about 635 nm. The light emitting device according to claim 1, wherein the first phosphor does not contain quantum dots. The light emitting device according to claim 1, wherein the first phosphor comprises quantum dots. The light emitting device according to claim 1, wherein the first phosphorescent system is directly disposed on the semiconductor light source. The light emitting device of claim 1, wherein the light emitting device does not include a filter that creates a recess between about 550 nm and about 590 nm.

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